| Northern Manhattan and the South Bronx are sites of a disproportionate number of diesel particulate matter (DPM) sources, including an extensive network of highways and truck routes, seven out of the eight bus depots serving New York City and the largest food distribution center in the world, located at Hunt's Point in the Bronx. In this study, our aim was to characterize the residential-level spatial variations in traffic-related elemental carbon (EC), a surrogate for DPM, and PM2.5, using a set of 102 indoor and outdoor measurements collected as part of the Columbia Center for Children's Environmental Health's Mothers and Newborn Study. Second, a land use regression (LUR) model was developed to estimate exposure to ambient EC, using these outdoor residential EC measurements as the dependent variable and traffic-related spatial and temporal variables as predictors. Mean outdoor residential concentrations were 0.76 μg/m3 (SD 0.53) and 23.4 μg/m3 (SD 18.7) for EC and PM2.5, respectively. Both pollutants displayed higher variability than measurements taken at the central site location of the New York Botanical Garden (NYBG) as reflected in the coefficient of variation (residential EC: 0.70, NYBG EC: 0.40; residential PM2.5: 0.80, NYBG PM2.5: 0.45) The mean indoor-outdoor ratio for EC was 1.05 and 1.72 for PM2.5, indicating that indoor EC is dominated by outdoor sources. The final LUR model was able to explain 46% of the variability in outdoor residential EC concentrations. Significant predictors included in the model were NYBG EC measurements, atmospheric pressure, road area within a 500m buffer of the residence, distance to nearest truck route and year. |
